Selective Herbicides for Cultivation ofEucalyptus urograndisClones

Patrick J Minogue,Anna Osiecka

doi:10.1155/2015/341314

Abstract

Competition control is essential for successful eucalyptus plantation establishment, yet few selective herbicides have been identified. Five herbicides, flumioxazin, imazamox, imazapic, oxyfluorfen, and sulfometuron methyl, were evaluated for selective weed control in the establishment of genetically modified frost tolerantEucalyptus urograndisclones. Herbicides were applied at two or three rates, either before or after weed emergence, and compared to a nontreated control and to near-complete weed control obtained with glyphosate directed sprays. Applications prior to weed emergence were most effective for weed control and, with the exception of imazapic, all resulted in enhanced eucalyptus growth relative to the nontreated control. Among postemergent treatments, only imazamox enhanced stem volume. Among selective herbicide treatments, preemergent 2240 g ha−1oxyfluorfen produced the best growth response, resulting in stem volume index that was 860% greater than the nontreated control, although only 15% of the volume index obtained with near-complete weed control. Imazapic was the most phytotoxic of all herbicides, resulting in 40% mortality when applied preemergent. Survival was 100% for all other herbicide treatments. This research found the previously nontested herbicides imazamox and imazapic to be effective for selective weed control and refined application rate and timing of five herbicides for use in clonal plantations.

Highlights

Because of their adaptability and fast growth rates, Eucalyptus species and hybrids have been grown for fiber, fuel, landscaping mulch, essential oils, phytoremediation, and as ornamental trees [1, 2] on more than 17.8 million ha worldwide [3]
This study demonstrated that a single application of one of several selective herbicides over newly planted rooted eucalyptus cuttings may enhance their growth
preemergence of weeds (PRE) applications of the herbicides tested were more effective than post emergence of weeds (POST) applications and provided weed control during the critical period of tree establishment

Summary

Introduction

Because of their adaptability and fast growth rates, Eucalyptus species and hybrids have been grown for fiber, fuel, landscaping mulch, essential oils, phytoremediation, and as ornamental trees [1, 2] on more than 17.8 million ha worldwide [3]. The importance of vegetation management prior to planting eucalyptus is stressed by many authors [6, 7], and studies throughout the world have demonstrated that competition in the first eighteen months to two years following planting is most impactful [8,9,10] as fast growing eucalyptus trees at typical plantation densities (3 by 3.5 m) quickly close crown canopy, excluding light to the understory, limiting the growth of other vegetation. The development of a selective, broad spectrum herbicide, which can be sprayed over eucalyptus transplants and provide persistent weed control when applied either prior to weed emergence (preemergent) or to actively growing weeds (postemergent), would advance eucalyptus silviculture

Methods

Results

Conclusion